In general, semiconductor memory devices include volatile memory devices that may lose stored information when the power supply thereto is cut off and nonvolatile memory devices that may retain stored information even when not powered.
A flash memory device is a nonvolatile memory device, and in general includes a cell array region and a peripheral circuit region. A ground selection transistor and a string selection transistor are formed in the cell array region, and a plurality of cell transistors are disposed between the ground selection transistor and the string selection transistor. A low voltage transistor and a high voltage transistor are disposed in the peripheral circuit region. A common source line is disposed at one side of the ground selection transistor, and a bit line contact is disposed at one side of the string selection transistor and is electrically connected with a bit line thereon. Contacts, pads and lines that are electrically connected to the low voltage transistor and the high voltage transistor are disposed in the peripheral circuit region.
Since flash memory devices may include many contacts, pads and lines that are disposed in the cell array region and the peripheral circuit region, the manufacturing process for flash memory devices may be complex.